Abstract: Rareminnow, Gobiocyprisrarus, is aChinese cyprinid. It has many attractive features that make it a suitable organismin aquatic toxicity tests, including small size, wide temperature range, easily being cultured in laboratory, large amount of eggsand short life cycle. It has also been reported this species is susceptible to heavy metals and other xenobiotics. However, littlehas been known about the endocrine disruptions of xenoestrogens in this native Chinese species. The aim of the study was to in vestigate the effects of diethylstilbestrol (DES) exposure in early life stage on development and reproduction of rare minnow.Rare minnowwere raised in the laboratory. Theyweremaintained in a light/ dark cycle of 14B10 h at 23226 e and fed oncea day1To start the test with DES, embryos ( < 8 h postfertilization) were collected from at least three spawnings as required bystandard protocol1 Based on a 28 days preliminary exposure study, nominal concentrations of DES at 10 and 100L g/ Lwere se2lected for this study1 Rare minnowwere exposed to these two concentrations of DES from newly fertilized embryos to 23 daysposthatch1Themortality, abnormal behavior and appearance of the larvae were recorded during the exposure1At the end of expo2sure. fish were sampled to measure body weight, body length and then stored at - 80 e for V TGanalysis andTotal T4(TT4)mea2surement1 At 24 days posthatch, rare minnow were transferred to clean water1 At 175 days posthatch, 15 fish were sampled tomeasure bodyweight, body length and then stored at - 80 e for Vtg analysis1 Four mating pairs were selected from control groupand DES 2exposed groups for examination of fecundity and fertility1At the end of exposure, it was found that exposure to DES caused an increase in mortality and vitellogenin(V TG) lev2els1Growth was significantly inhibited in the fish exposed to DES1After a five2month period culture in clean water, the sex ratio(male: female)observed was changed from46: 54 in controls to 31: 69 at 10Lg/ LDESand 33: 67 at 100Lg/ LDES1Reproductivecapability was depreciated in the DES2treated fish as measured by fertility of eggs, hatchability of eggs and survival of F1lar2va1The growth and V TGlevel had a significant change in the DES 2treated fish when compared to the control group1The results in2dicate that exposure to DES in early life stage can cause adverse effects on development and reproduction1It suggests that rareminnow is suitable for early life stage test in assessing the environmental impact of endocrine 2disrupting chemicals.